We propose an investigation of the motion of the right ventricle (RV) in the mongrel dog, using Roentgencinefluorography and the mathematical theory of affine mapping. Under sterile conditions, radiopaque markers (1.2 by 2 mm tantalum screws) are implanted transpericardially. A miniature pressure transducer is installed in the mid-ventricle to monitor RV pressure and heart sound. In a biplane x-ray system, the heart of the unanesthetized animal is filmed with high-speed cameras at 300 frames/sec under 85 kV x-rays. We plan to study the alterations in myocardial contractile behavior due to acute volume and pressure overload and change in inotropic state.